This invention pertains to the casting of cement and/or concrete objects, and particularly to methods and materials for increasing the lives of the forms which are employed therein.
The introduction of a fluid cement and or concrete into a cavity, or mold, where upon solidification, the resulting casting becomes an object whose shape was determined by the mold, is an old art. In this molding process a wood, metal or plastic form is fabricated in the shape of the part to be produced. Materials are then compacted around the form in such a way that the mold and the pattern can be removed, leaving a cast object in the shape of the form.
It is well known that to increase the life of the forms (wood, metal or plastic) and to make the removal of the casting easier, the surfaces of the mold cavity must be coated with a protective material.
Prior art coating compositions however deal primarily with film forming form release coatings made by blending of petroleum based oils with organic additives such as oleic acid, waxes, paraffin, and the like.
Coatings for the concrete and cement industry are basically form release agents. They are used to obtain smoother casting surfaces with fewer defects. The cast surfaces of the concrete and/or cement erode and pit when successive forms are produced using them. When such erosion occurs, concrete and/or cement have a greater tendency to adhere to the pattern when it is removed, affecting the cast surface. Petroleum based mineral seal oil and mineral seal oil-oleic acid form release coatings are presently the commercial preference. By contrast, the vegetable oil based form release coatings in accordance with the present invention are biodegradable and provide improved release properties and increase the number of molds/application.
The present invention relates to a method of protecting cast cement and/or concrete from eroding and pitting during casting by preventing adherence of casting surfaces using a biodegradable and low VOC (Volatile Organic Compound) form release coating applied to the form. In accordance with one aspect of the invention, the method involves applying a biodegradable vegetable oil composition to the surfaces of a form in an amount sufficient to form a coating which prevents adherence and affords the necessary protection. The coating composition in accordance with one embodiment of the present invention relates to a biodegradable blend of vegetable oil with petroleum oil and/or alcohol. In accordance with another embodiment of the present invention, the coating composition is an emulsified vegetable oil, and the clay incorporated therein is an organophilic clay, included in the coating as such or as a clay water dispersible amine mixture. The emulsion, then, is a 40/60 by weight oil emulsion.